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An enabled window larger than PCI_BUF_SIZE lets the bridge expose DMA addresses beyond the allocation. The character device read/write paths also derive their bounds from vme_get_size(), so the oversized programmed window can make buffer_to_user() and buffer_from_user() access past image[minor].kern_buf. Reject enabled slave windows that do not fit in the backing buffer and use the same capped size for slave read/write/llseek bounds. Also convert the read/write limit checks to subtraction-based form so offset + count cannot wrap around the image size check. Signed-off-by: Yousef Alhouseen --- drivers/staging/vme_user/vme_user.c | 38 ++++++++++++++++++++++------- 1 file changed, 29 insertions(+), 9 deletions(-) diff --git a/drivers/staging/vme_user/vme_user.c b/drivers/staging/vme_user/vme_user.c index 11e25c2f6..24d3c6ec3 100644 --- a/drivers/staging/vme_user/vme_user.c +++ b/drivers/staging/vme_user/vme_user.c @@ -175,11 +175,22 @@ static ssize_t buffer_from_user(unsigned int minor, const char __user *buf, return count; } +static size_t vme_user_get_image_size(unsigned int minor) +{ + size_t image_size = vme_get_size(image[minor].resource); + + if (type[minor] == SLAVE_MINOR) + image_size = min_t(size_t, image_size, image[minor].size_buf); + + return image_size; +} + static ssize_t vme_user_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { unsigned int minor = iminor(file_inode(file)); ssize_t retval; + size_t offset; size_t image_size; if (minor == CONTROL_MINOR) @@ -188,17 +199,19 @@ static ssize_t vme_user_read(struct file *file, char __user *buf, size_t count, mutex_lock(&image[minor].mutex); /* XXX Do we *really* want this helper - we can use vme_*_get ? */ - image_size = vme_get_size(image[minor].resource); + image_size = vme_user_get_image_size(minor); /* Ensure we are starting at a valid location */ - if ((*ppos < 0) || (*ppos > (image_size - 1))) { + if ((*ppos < 0) || ((u64)*ppos >= image_size)) { mutex_unlock(&image[minor].mutex); return 0; } + offset = *ppos; + /* Ensure not reading past end of the image */ - if (*ppos + count > image_size) - count = image_size - *ppos; + if (count > image_size - offset) + count = image_size - offset; switch (type[minor]) { case MASTER_MINOR: @@ -223,6 +236,7 @@ static ssize_t vme_user_write(struct file *file, const char __user *buf, { unsigned int minor = iminor(file_inode(file)); ssize_t retval; + size_t offset; size_t image_size; if (minor == CONTROL_MINOR) @@ -230,17 +244,19 @@ static ssize_t vme_user_write(struct file *file, const char __user *buf, mutex_lock(&image[minor].mutex); - image_size = vme_get_size(image[minor].resource); + image_size = vme_user_get_image_size(minor); /* Ensure we are starting at a valid location */ - if ((*ppos < 0) || (*ppos > (image_size - 1))) { + if ((*ppos < 0) || ((u64)*ppos >= image_size)) { mutex_unlock(&image[minor].mutex); return 0; } + offset = *ppos; + /* Ensure not reading past end of the image */ - if (*ppos + count > image_size) - count = image_size - *ppos; + if (count > image_size - offset) + count = image_size - offset; switch (type[minor]) { case MASTER_MINOR: @@ -271,7 +287,7 @@ static loff_t vme_user_llseek(struct file *file, loff_t off, int whence) case MASTER_MINOR: case SLAVE_MINOR: mutex_lock(&image[minor].mutex); - image_size = vme_get_size(image[minor].resource); + image_size = vme_user_get_image_size(minor); res = fixed_size_llseek(file, off, whence, image_size); mutex_unlock(&image[minor].mutex); return res; @@ -394,6 +410,10 @@ static int vme_user_ioctl(struct inode *inode, struct file *file, return -EFAULT; } + if (slave.enable && + (!slave.size || slave.size > image[minor].size_buf)) + return -EINVAL; + /* XXX We do not want to push aspace, cycle and width * to userspace as they are */ -- 2.54.0